The present invention relates to catheters for insertion into a body lumen. More particularly, the present invention relates to a "focal" balloon dilatation catheter for use in the vascular system.
Prior art vascular dilatation balloons on typical dilatation catheters tend to fall into one of two broad classes. Most are considered noncompliant balloons, formed from a generally nondistensible material such as polyethylene. The perceived advantage of the noncompliant balloons is that they exhibit a substantially uniform exterior inflated profile which remains substantially unchanged upon incremental increases in inflation pressure. In theory, noncompliant balloons are advantageous because they allow the introduction of increased inflation pressure to break particularly calcified lesions, yet retain a predictable inflated profile so that damage to the surrounding native lumen is minimized.
Certain compliant balloons are also known in the art. A compliant balloon is one which is able to grow in diameter in response to increased inflation pressure. One difficulty with compliant balloons, however, is that inflation within a difficult lesion can cause the balloon to inflate around the plaque to produce a generally hourglass-shaped inflated profile. This can result in damage to the native vessel adjacent the obstruction, while at the same time failing to sufficiently alleviate the stenosis.
Therefore, there exists a need in the art for a vascular dilatation catheter with a balloon which is able to grow in diameter in response to increased inflation pressure, and which expands in a predictable inflation profile while minimizing any damage to the native vessel.